Thermoset resins, including unsaturated polyesters, are commonly employed in a variety of fabrications, such as casting materials, fiber reinforced materials and gel coats. Many of the composite articles fabricated from thermoset resins are used in environments exposing them to ultraviolet light, solvents or water. Prolonged UV and water exposure of composite articles derived from conventional unsaturated polyester resins often results in degradation of the article, which can be evidenced by blister formation, fiber prominence, loss of color and yellowing.
Many technologies have been disclosed in patents and general literature for improvements in weatherability of composite articles derived from unsaturated polyester resins. Available technologies have either claimed improved UV resistance or improved hydrolytic stability over conventional systems.
Therefore, a need exists for high performance UV and water resistant unsaturated polyester resin compositions which will also meet the U.S. EPA limits for MACT compliance for hazardous air pollutants (HAPs).